Device for dressing grinding wheels



Ot. 11,1938. HDANNER 7 2,13

' DEVICE FOR DRESSING GRINDING WHEELS Filed Aug. 20, 1937 2 Sheets-Sheet l Inventor m mm? X Oct, 11, 1938. H. DANNER A DEVICE FOR DRESSING GRINDING WHEELS 2 Shegts-Sheet 2 Filed Aug. 20, 1937 Lil retested 11, 1938 E T NT OFF'ICE fabrik statt,

tga'rt, Germany, assignor Application sum 20, 1931, Serial No. 160,183 A i In Germany April 6, 1936 12 Claims. ('61. 125-11) This inventionqelates to a machine or device -for dressing stepp d shouldered profile grinding wheels, wherein hydraulic drive mechanism is provided for efii'ciently operating the machine in accordance with the so-called copying" method. In dressinggrinding wheels of the shouldered profile typ and by means of a diamond tool while is guided in its operation by means of a template, care must be exercized in lowering the diamond tool from one-shouldered surface to theinext lower shouldered surface of the grindin'g wheel, and this'in order that said operation may be accomplished accurately -and without shock, thus avoiding damage or injury, to either the dressing tool orthe grinding wheel. For this reason dressing machines -'or devices have heretofore been constructed exclusively for hand' operation, and this-in turn leads to defects in the accuracy \of the work'produced, 'of which the most serious is that the feediof the diamond tool over the operating surface of' the grinding wheel, (which is usually accomplished by means of a hand operated screw drive), is not of suf-- ficient uniformity: and with any degreeeof ex.- 25 actness. The reason for this is that the operator; cannot concentrate his attention solely upon maintaining acertain speed offered, and in addition to this, saidoperator must exercise utmost care at the points where the shoulders are formed w in order to alter the position of the diamond tool 1 rives'at a predetermined step or shoulder of the,

profile to. be operated. upon, and wherein the dlmechanicalmeansmaybesoadiustedandarranged as to control the operation of the machine for use 'in connection with grinding wheels of varying profiles. I

Theinvention comprises a template for guid- Ming the dressing tool in asscciationwith a end-- trolmemberor-rail for the hydraulic drive of the dressing tool, said control member being connected to theslide carrying the dressing tool and effecting in association with other mechanismv the Iintsrruptionof the supply of pressure ,ment is achieved over-existing methods.

the hydraulic slide drive mechanism during the constant feeding. operation" of the dressing tool. thus stopping the feeding movement of said dressing tool, in an efllcient' manner, andthis I whens, suitably provided guide pin or member, associated with the dressing tool, reaches a shoalder-of the template corresponding to the shoulder on the grinding wheel at the end of the grind- 'ing wheel surface just previously dressed.

In this arrangement, the operator sets the desiredfeed velocity of the diamond tool at the beginning of the dressing operation, and ,this feed velocity remains unchanged during the dressing operation of each shouldered surface,- v whereupon .the diamond tool is stopped posiv tively, withcertainty and accuracy at the points where it is to be reset for the dressing of another shouldered surface. The'operaton has at hisdisposal any required amount of time for the resetting operation, and therefore may devote i the necessary attention thereto. This dressing operation maybe continued at the will of the operator .andby means of a hand controlled lever for the resetting operation, "whereupon the 1 diamond tool again moves forward; with the 25 originally selected feeding speed to perform its dressing operation up to the next shoulder on the profile or to the end of the profile as'the case'maybe. Furthermore, the invention requires that the means for stopping the hydraulic drive be so constructed and arranged that said means shall be capable of altering the speed of the diamond tool in its movement in a direction parallel to the grinding wheel axis, and this in a positive.

manner and according to a predetermined plan to suit conditions; This embodiment of the invention is important in the case. of profiles which at various points-require the feeding movement of the diamond tool to be composed of two per- 0 pendicular components and, without shouldered or step jumps, the condition being that the diamond tool shall treat all sectionsof the grinding wheel profile at the same speed. Accordingly, v at the points where the diamond tool moves at 45' an angle'with respect to-the grinding wheel axis,

its speed must be reduced in the direction of said.

- This requirement" is dimcult t0 fulfill, and

cannot-be accomplished in a satisfactory man-" nerf by hand operating devices. but with a magqchine constructed in accordance with the pres-' ent invention, this problem may be readily solved, whereby further remarkablei.-; improvean embodiment of the improved' mac'hine or gs device according to the present invention is illustrated by way of example in drawings wherein: Figure 1 is a diagrammatic viewof a piece of work of the type to-be ground by a shouldered grinding wheel using the plunge cut method; and also illustrating in connection therewith the type of grinding wheel which is to be dressed; Figure 2 isa side elevation of the improved dressing machine; Figure 3 is a front elevation thereof; and Figure 4 is a top plan view of the dressing machine as shown in Fig. 3.

The embodiment of this invention is based upon the conditions as illustrated in Figure l, and wherein it is necessary to dress grinding wheels of the type used for grinding work havinga number of shouldered portions, and this by the plunge cut method: In this Fig. 1 disclosure, a cylindrical part a of the work having a comparatively'small diameter is joined by a second cylindrical portion b of slightly larger diameter which is followed by a third cylindrical portion c of still larger diameter. Furthermore, a frustoconical portion d, increasing in diameter towards the left, leads to'the last cylindrical portion e. These portions 0, b and c are shouldered oi! at right angles with reference to one another as shown in Fig. 1. For grinding this type of work by the plunge cut method, i. e., by feeding the grinding wheel S radially toward the axis of the work, the surface of the grinding wheel with its individual adjacent surface portions, must have its diameter graduated accurately in accordance with the measurements-when considering the diameter of the work, but in inverse relation thereto, the smallest diameter of the work corresponding to the largest diameter of the grinding wheel and vice verse. I

It is, therefore, the "essence of this invention to provide a machine or device which is capable of dressing profiles of grinding wheels of the type Just referred to, and this machine comprises a block shapedframe l and a diamond tool holder 2, mounted on the'frame so as-to be slidable in two directions at right angles to each other, The frame I is fixed relatively to the grinding wheel, as for instance, onthe upper part 2 of the grinding wheel slide or mounting. On the frame -l is mounted a hydraulic drive 4; S for moving the diamond tool holder 2 over the working surfaceof the grinding wheel, and also mounted on said frame are the parts necessary for the control of said drive. The axis of the hydraulic drive 4, Send the front surface of the irame I are parallel to the axis of the grinding wheel. This frame has a" horizontal dovetail guide 6, upon which the base slide. 1 or the diamond tool holder moves. ,The slide 1 isconnectedby means of an arm. 8 to the piston rod 9 of piston}, which piston is adapted to reciprocate within the cylinder 4, to which cylinder liquid under pressure is supplied through conduits |0il for moving the piston in one direction or the other, according to the position of a hand operated reversing valve bodimen't shown, and serves to control the speed of the feeding movement. of the slide I which ,carries the tool holder. 7

It is to be noted that the front surface of the slide I is also formed as a dove-tail guide i4, dis

the accompanying In the example shown (see Figs. 2 and 4) a selflocking rack and pinion mechanism I8 is provided for the rapid vertical reciprocable movement of the diamond tool holder 2 in the guide 14.

As previously mentioned, the diamond tool -is set and controlled for the dressing of the various grinding wheel diameters or surfaces required, by means of a template i9 which is detachably secured to the upper front edge of the frame I. Its freely exposedupper surface is an accurate replica of the desired profile of the working surface ofthe grinding wheel, and "serves as a guide surface for the guide pin or member 20, which is carried by an arm 2| extending from the diamond tool holder 2. The pin 20 is shouldered as at 20 on. one side of its free end and with its center plane perpendicular to the grinding .wheelaxis,

the working edge of the diamond I! being also 'locatedin said plane. With the surface 20' thus formed, the diamond tool holder 2 is set (and this prior to the lowering from one shoulder at the template I! to the next lower shoulder) accurately to the plane of the template shoulder, and during'iowering isheld-fastin said plane. According to the invention, this is effected by positively interrupting the transverse feeding movement of the diamond holder 2 (produced by the piston drive 4, by mechanical means adjustable with the necessary accuracy, as soon as the guide pin is in the correct position on the template I2. I

In the embodiment of the invention as shown particularly in Figs. 2 and 4, a controlling member or rail 22 is mounted for the purposes intended in a slidewayin the base slide l of the' J diamond tool holder 2 opposite the front surface of the frame i,'said rail having notches 23, 22', 2l", 2l"., etc., corresponding in number to the shoulders of the template i9, which notches in association with other mechanism, serve for the control of the shut-off and control valvesl3 in the following manner:

The valve spindle 24 of the valve l2 carries a two-armed lever 25, the arms of which are of unequal length. The longer arm 26 forms a handle for manipulating and operating the mechanism, while the shorter arm engages with a cylindrical pin 21 in a sleeve 28, which sleeve has 'screw threaded engagement as at 29 with a rod 32 slidable in guides 30, 2| perpendicularly arranged with respect to the controlling member or rail 22. The guide 20 near the front surface of the frame iis widened to form a cylindrical bore in which the rod 32 is guided by means'of a "collar 22 on said rod 22, the inner surface of which collar acts as a movable support for a compression spring 24, the other end of which spring abuts the bottom of the guide bore 20." The end of the rodfllllocated in front of the collar 22 is formed as a tooth 35, adapted to fit inone of the notches 23, 23', 231, 23", etc. in the rail 22.

' The spring 34 maintains the rod 32 with the tooth ll pressed against the rail' 22, this tooth being projected in an outward direction, and accordina to its position with respect to the said rail, may

be pressed against the edge thereof, or into one of therecesses 22, 22', -23" and 22", As long as the tooth is in contact with the edge of the rail as just set forth, the'valve I3 is in its openposition. As

his

will more clearly appear hereinafter,'the passage area of the valve. may be varied within definite limits by the adjustment of the sleeve 26 on the threaded portion 23 of the rod 32 and in this manner it is possible to set the speed of the slide I and with it that of the diamond tool along the surface of the grinding wheel, as may be desired. When the tooth 33 snaps into any one of the hatches of the rail 22, the lever 26 is moved counter-clockwise, whereupon the valve I3 is closed and the slide I and its tool holder instantly stopped from further feeding movement.

It will be seen that for obtaining the desired control action, it is only .necessary to set the rail 22 opposite the template l9 insuch a manner that one of the notches 23. 23', etc. is directly opposite the tooth 36 on the rod 32, and this when the surface 26' of the guide pin is positioned at the shoulder of the template I! corresponding to the particular notch in question. To accomplish this end, a flne adjusting means is provided for the rail 22, and in the embodiment shown this means is in the form of an adjusting screw 36 which is suitably connected to the rail at one end thereof and serves to move the same backward and forward within its slidewaye After the automatic stopping of the slide I, the operator may now move the diamond tool holder 2 freely and in a downward direction by means of the rack and pinion I3, until the guide member or pin 20 bears against the next lower shouldered surface of the template IS. The operator then moves the hand lever 26 in a clockwise direction I, until the rear end of the rod 32 abuts against a movable abutment 31 disposed in the bearing 3|, and in this position of the rod 32, the tooth 35 is withdrawn to a slight extent beyond the edge of the rail 22, and furthermore, the valve I3 is again opened to permit further feeding movement of the slide I and its tool holder so that the tool may operate on the shouldered surface of the grinding wheel just selected. As will be readily understood, the rail 22 will be moved along with the slide I and after said rail has moved a slight distance, or in other words, when the previously engaged notch in said rail has moved beyond the tooth so that the smooth edge of said rail is opposite said tooth, then the operator may release the lever 26, as the valve is now maintained in open position by the engagement of said tooth 36 with the'smooth' edge of the control rail 22. Thus the rod 32 is supported as before by the control-rail, and as the feeding movement of the dressing tool progresses, said rod will be, so supported until the next notch in the control rail is brought opposite the tooth 35, whereupon said tooth snaps into stopped in the same manner at the-completion,

of the dressing operation by the notch 23".

said notch, and the valve is moved to closed position to stop further feeding movement as above described.

It is also to be noted that the slide .1 may be After said slide has been so stopped, the operatorraises the diamond tool 2, with the aid of the. rack and pinion drive I8 to the full height of the profile; sets the reversing v'alve l2 to proper position for reversing: and thereupon turns the hand lever 26 in a clockwise direction to move rod 32 into engagement with abutment 31 against the tension of spring 33 until the extreme position of the rod 32, in the direction in which it is moved,

is reached. The valve 13 is' thereby set to its full open position and the slide returns together withthe diamond tool holder 2' and the control while the slide I is at standstill;

rail 22 with comparatively rapid speed to its initial position, which is conveniently determined hand end' of the cylinder 6, as will be readily understood. In this position the slide may. be held by a notch 23" in the rail 22, into which by the abutment of the piston 4 against the right the tooth. 36 enters when operator releasesthe' hand lever 26 to prevent'further operation of the hydraulic drive. After the diamond tool holder has been lowered where the guide pin or member again rests on the template IS the device is ready for the next period of operation.

According to the invention a constant speed of. the dressing diamond over-all parts of the; grinding wheel profile should be maintained with the aid of the hydraulic drivel; 6. Therefore, provision mustbe made for the frusto-conical surface, with which the grinding wheel must act upon part-d of the work (to be passed over bythe diamond during the dressing operation), and at the same speed as any of the cylindrical 'surfaces of the parts a, 11,0 and e. This requires, as mentioned above, the reduction of the speed of the slide I in the direction of the guide 6 on the axial length of the part d, since 'on this stretch the diamond must be simultaneously moved in horizontal and vertical directions. The vertical displacement is effected by means of the rack and pinion drive I6. The speed reduc-' tion for the movement of the slide I on the guide 6 can be achieved with the means described by means of a notch 39, .which is shallower than the other notches and thus, when the tooth 35 snaps into said notch, it effectsmerely throttling, but not complete closure of thevalve I3. The.

extent of throttling follows from the condition which islocated in the front,in the direction of v movement of the slide 1, must be shouldered off at right angles, to initiate suddenly the change of speed whenthe guide pin passes onto the incline, but that the exit or tail edge of the means of the rack and pinion drive I3, an autonotch must be inclined so as to cause the toothv 35 to. be positively lifted out of the notch-39. f The described method of speed regulation is also applicable to profiles, which'in'clude curved. portions continually merging one into the other.

maticallyoperating-hydraulic or mechanical de- 1 vice may beprovided, which may be so, fltted into. the cycle of.;'operations that the device is rendered thereby fully" automatic.. The changes in the directions of movement of the slide I may. also be render'ed positive in known manner by means of abutinents cooperating with the revers-' ing valve I2. The important point is that in. all

arrangements the diamond tool passes over? from one shoulder diameter to the next. lower-one I-claim is: l-. -A machine for dressing template carried by said frame, a" tool holder mounted for movement 'uponsaid frame,

7o o der d ofile grinding wheels, comprising a fixed frame, a

in engagement with the template for guiding and controlling the tool holder and its dressing tool during the dressing operation, hydraulic mechanism for reciprocating said tool holder for feeding the too] over the work, and a control member also mounted on saidv tool-1' holder and in cooperative relation with the hydraulic mechanism for stoppingthe feeding movement of said too], said control member movable with said tool;

holder to permit the desired feeding movement of the tool and thereafter effecting interruption-- of the fluid pressure to said hydraulic mechanismwhen the guiding member reaches a predetermined point on the template.

2. In a machine according to claim 1, wherein a valve is provided in the hydraulic system for interrupting the supply of fluid pressure to said system at each profile shoulder of the grinding wheel and wherein said valve alsocontrols the feed velocity of the dressing tool during th operating stroke of said tool.

3. In a machine of the character set forth according to claim 1, wherein the mechanism for stopping the feeding movement of the dressing tool at each profile shoulder, is released to permit restarting of the tool for another of the series of predetermined work operations during each complete stroke of the tool, and also released for the rapid return of the tool to its I dressing tool with respect to the grinding wheel profile surface, and also for intermittent closing of the valve to permit accurate stopping of said feeding movement of the dressing tool when reaching a profile shoulder on the grinding wheel.

5. In a machineaccording' to claim 1, wherein the control member operates a valve for stopping the feeding movement of said dressing tool holder when reaching a profile shoulder on the grinding wheel.

6. In a machine according to claim 1, wherein the controlmember may be adjusted in accordance with: conditions surrounding any. particular dressing operation.

the purpose of controlling-the feed velocity of, the dressing tool during the operating stroke Of said tool.

10. In a machine according to claim 1. wherein the control member or rail is adjustable with respect to the template and its cooperating tool holder guiding member for the purposes intended.

11. In a machine according to claim 1, wherein the control member is slidably mounted on the tool holder and capable of being moved in a direction in line with the feeding movement of the tool holder and also adapted to be held in any one of a number of adjusted positions thereonby meansof an adjusting screw.

12 In a machine according to claim 1, where- 86 inthecontrol member cooperates with the hydraulic mechanism to throttle the same and reduce the ieeding'speed of the dressing tool when operating on grinding-wheels or other work having frusto-conical portions and before effecting complete interruption of the fluid pressure for stopping the feeding movement of the tool. HERMANN DANNER. 

